Liu Lining, Bianconi Simone, Wheaton Skyler, Coirier Nathaniel, Fahim Farah, Mohseni Hooman
Bio-Inspired Sensors and Optoelectronics Laboratory, Northwestern University, 2145 Sheridan Rd, Evanston, Illinois 60208, USA.
ASIC Development Group, Particle Physics Division, Fermi National Accelerator, Batavia, Illinois 60510, USA.
APL Photonics. 2025 Mar 1;10(3):036106. doi: 10.1063/5.0233887. Epub 2025 Mar 3.
Increasing the energy efficiency and reducing the footprint of on-chip photodetectors enable dense optical interconnects for emerging computational and sensing applications. While heterojunction phototransistors (HPTs) exhibit high energy efficiency and negligible excess noise factor, their gain-bandwidth product (GBP) has been inferior to that of avalanche photodiodes at low optical powers. Here, we demonstrate that utilizing type-II energy band alignment in an Sb-based HPT results in six times smaller junction capacitance per unit area and a significantly higher GBP at low optical powers. These type-II HPTs were scaled down to 2 m in diameter and fully integrated with photonic waveguides on silicon. Thanks to their extremely low dark current and high internal gain, these devices exhibit a GBP similar to the best avalanche devices (∼270 GHz) but with one order of magnitude better energy efficiency. Their energy consumption is about 5 fJ/bit at 3.2 Gbps, with an error rate below 10 at -25 dBm optical power at 1550 nm. These features suggest new opportunities for creating highly efficient and compact optical receivers based on phototransistors with type-II band alignment.
提高能量效率并减少片上光电探测器的占用面积，可为新兴的计算和传感应用实现密集光学互连。虽然异质结光电晶体管（HPT）具有高能效且过剩噪声因数可忽略不计，但其增益带宽积（GBP）在低光功率下一直低于雪崩光电二极管。在此，我们证明在基于锑的HPT中利用II型能带排列可使单位面积的结电容减小六倍，并在低光功率下显著提高GBP。这些II型HPT的直径缩小至2微米，并与硅上的光子波导完全集成。由于其极低的暗电流和高内部增益，这些器件展现出与最佳雪崩器件相似的GBP（约270吉赫兹），但能量效率提高了一个数量级。在3.2吉比特每秒的速率下，其能耗约为5飞焦/比特，在1550纳米波长、-25分贝毫瓦光功率下误码率低于10。这些特性为基于具有II型能带排列的光电晶体管创建高效紧凑的光接收器提供了新机遇。
